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X Particle Might Explain Dark Matter & Antimatter
cold fjord writes "Wired Science has a story on a new theory that tries to explain dark matter, and the balance of regular matter with antimatter. This theory may even be testable. From the article: 'A new hypothetical particle could solve two cosmic mysteries at once: what dark matter is made of, and why there's enough matter for us to exist at all."
What gives the X-Men their powers.
You'll need to come with me. Room 101 is waiting.
Humans are terrible replicators of Godly things.
Yes, but why?
That's the question that needs answering. We see that there is matter, obviously, but common sense (assuming the big bang is accurate, and it has held up pretty well over the years) says their shouldn't be.
So why does matter exist? Why didn't matter and anti-matter annihilate each other evenly? They've tested it in the colliders, and sure enough, matter and anti-matter are not created equally given the conditions necessary to create them.
This is a theory to explain why what is, is. This is how science works. You take an observable fact, create a hypothesis for why it might be so, and test the hypothesis. If it works as the hypothesis describes, you're closer to knowing why the observable fact is an observable fact. When you know a bunch of reasons why observable facts exist, you start to be able to predict new things that you haven't observed yet, and you can start looking for them. If you don't find them, your theory is bunk. If you do, your theory may still be bunk, but you at least know it is pretty good.
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The paper is also available at the arXiv if you don't have a subscription to Phys. Rev. Lett.
Why, oh why can't people posting science stories on slashdot post links to the actual papers when they're publicly available? http://arxiv.org/abs/1008.2399
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Wow, haven't been following physics much, eh?
Security is mostly a superstition... Avoiding danger is no safer in the long run than outright exposure. - Helen Keller
"This theory may even be testable."
To be a theory it must be testable.
If Slashdot were chemistry it would look like this:Cadaverine
Yes, because as we all know, the 'black' in 'black hole' is a reference to ignorance, not a reference to its light-capturing property.
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Equal amounts of X and anti-X were created in the Big Bang, and then decayed to lighter particles. Each X decayed into either a neutron or two dark-matter particles, called Y and . Every anti-X converted to an anti-neutron or some anti-dark matter.
But the hypothetical X particle would rather decay into ordinary matter than dark matter, so it produced more neutrons than dark matter. Anti-X preferred decaying into anti-dark matter, and so produced more of it.
Bold emphasis added is mine. Does this theory explain why "particle X" would rather decay into ordinary matter? Isn't that begging the question? How is that any different than moving to the larger set of all mass, and just saying "Hypothetical universe X would rather form more ordinary matter than dark matter". I understand they may be foregoing the DiffyQ's that perhaps stand behind their assertions for the word "rather" to provide for the layman, but this premise kills the theory for me unless there exist math/science/evidence/a reason besides the word "rather for this article.
'We are trying to prove ourselves wrong as quickly as possible, because only in that way can we find progress.' RPF
There's a difference between "testable in theory" and "testable in practice". Science proceeds from both ends towards the middle, where theoreticians and experimenters meet.
Theoreticians work on things that may not be testable in practice, now. They may be testable one day, and that actually happens: particle physicists build bigger colliders, astronomers get to see the views they couldn't before, paleontologists dig up the fossil they expected but didn't have.
It leaves the realm of science utterly when it's not testable even in theory. Between the two there's a gray area, where something may not be practical in the forseeable future, or may require so much time and space and energy that it's absurd to think it would ever become practical. Theoreticians run a minefield here, but it would be invalid to forbid them from going there. They might well find a way to take something absurd and make it realistic; it happens.
I'm glossing over a lot of epistemic niceties here, but the point is that a theory does not have to be testable at the moment to be science. If this one happens to be testable now or in the near future, yay; that lets us exclude a lot of territory that's currently in the mine field. But it likely would not have happened without other theoreticians having explored that space.
just put a crowbar by the testing lab
Which ones specifically? In fact, I challenge you to name even one theory that isn't testable. And String theory doesn't count. It's about as scientific as Astrology.
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Axiom of Choice?
That brings me to an interesting point, / . is just "the ramblings of socially-inept, technology-literate news-mongers".
From TFA:
The signature of dark matter destroying protons “can be easily tested by the even bigger proposed underground detectors” planned to be built somewhere in Europe.
Should anyone interested in science just move to Europe now? Seems to be the place in the world where people actually care about science these days.
"Convictions are more dangerous enemies of truth than lies."
God damnit, no, it doesn't explain all dark matter. It explains how some antimatter could appear in cosmological equations as dark matter.
There's a lot of "dark matter" which really isn't all that dark (in the sense of "unknown") anymore. In cosmology, dark matter is just anything with mass which isn't conventionally visible from here. We can ballpark how heavy the universe should be based on the equations we've figured out for how the universe works in our neighborhood. Then we can turn around and observe as much as possible in the way of galaxies and so forth and total up how much mass that should represent. The balance is dark matter - it is no more nor no less mysterious than that.
We already know what some types of dark matter are. For example, it is hard as hell to get neutrinos show up, but they are probably one of the most abundant things in the universe. As a rule, the only way we can see them is if there are enormous epic-scale bucketloads to the infinity power of them sweeping by us all at once (as there usually are!)...and at that point we catch maybe one neutrino that smacks into an easier-to-observe atomic particle exactly on target (on the scale of the infinitesimally small particles involved). By extrapolation, we reason that the rest of them must be there as well, because we can calculate what the exceedingly minute probability was for the one event that we actually saw.
Other types...who knows? Maybe the guys referenced in the article are on to something. But it would be a relief if we could actually report the contents of the research rather than making up a bunch of malarkey which just gives people silly ideas about how the universe works. The truth is far stranger, there's no need to make stuff up.
To be a theory it must be testable.
Prove it.
rewriting history since 2109
In fact, I challenge you to name even one theory that isn't testable.
P = NP.
Your move.
The axiom of choice is an axiom, not a theory. Coincidentally, this is why it is not called the theory of choice.
And String theory doesn't count. It's about as scientific as Astrology.
A Slashdotter or hundreds of physicists... who's a fellow to believe?
String theory (variants thereof) conforms to observations as well as any other theory. What's lacking is an observation where the predictions diverge.
Until such time as such an observation becomes possible, if you want to knock string theory you should argue on the basis of Ockham's Razor, not on perceived parallels with astrology.
Sheesh, evil *and* a jerk. -- Jade
Yes, it's because it doesn't emit (except for the Hawking radiation) but it's still a name of ignorance: the existance of the singularity proofs Einstein's general relativity as wrong but we still lack a better theory to substitute it.
Actually it's the opposite.
The existence of singularities was a major prediction of General Relativity, and the source of much skepticism towards the theory. People didn't believe a thing like that could exist in our universe. The discovery of Black Holes with many of the predicted properties was (more) proof that GR was a damn good theory.
Not that we don't need a better theory to address known flaws, or that you couldn't in some way say Black Hole is a 'name of ignorance'. Certainly, there is a lot we don't know about them. If there is any problem with relativity wrt black holes, it's that since we can't look past the event horizon, we can't tell if there really exists a mathematical discontinuity in the universe or if something else is happening.
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Physicists going old-fashioned on us, eh?
Table-ized A.I.
That's actually one of the major problems with many of the current formulations of string theory; they're testable in theory, but in practice by the time we can throw that much energy around we probably won't care about the answer any more, one way or the other.
I'll be at the Tomohawk room in Chippewa tomorrow night if you want to discuss it.
I nominate Michael Krisotpeit as the 2010 /. Troll of the Year. We can send the award to all the fake addresses he keeps posting.
I swear, there hasn't been a troll this amusing since twitter. WHatever happened to him anyway?
Celebrity worship is a poor substitute for Deity worship and costs more to boot.
Well said sir! As an example, Frame-dragging was proposed as a theory in 1918 based on Einstein's theory of General Relativity but wasn't able to be tested until 1996 with a couple of special satellites and even then not accurately enough to be provable until 2006. Since we had barely left the ground let alone orbit the earth at that point I'm sure it must have seemed un-testable at the time.
This thread seems to have uncovered the secret behind the copious presence of Dark Matter.
It appears to be fecal matter.
"Flyin' in just a sweet place,
Never been known to fail..."
It is, however, entirely suited to making bad jokes on ./, for example:
Q: What's yellow and sour and equivalent to the axiom of choice?
A: Zorn's Lemon!
whenever two WIMPs meet up in space, they annihilate each other
I'm trying to picture this in my head, and failing.
Every end has half a stick.
Many of us with actual scientific backgrounds would call them hypotheses, not theories.
It's official. Most of you are morons.
Unfortunately such reasoning is certainly suspect in general -- Aristotle did it by postulating that nature was designed with niches to fit the various animals perfectly because he was unaware of the theory of evolution which has animals evolving into those niches -- but often quite successful in particle physics. The neutrino was first postulated totally arbitrarily to help explain weak decays and wasn't discovered for decades after, but people generally accepted it existed because the theory worked nicely. Much the same happened with things like W and Z bosons which weren't detected for ten or fifteen years after they were postulated to fit the symmetries of an apparently arbitrary theory. The current example is the Higgs' boson which we've *still* not discovered but which will cause ructions across all of high-energy physics if it doesn't exist.
That doesn't mean I *like* it. I get a distinct flavour of epicycles from a lot of this kind of thing too, but I can't deny it works.
(For the record, I hope the Higgs' doesn't exist. We'll have to junk about 50 years worth of theory and I quite like the idea of rebuilding without basing the whole lot on ideas from QED and group theory.)
If there is any problem with relativity wrt black holes, it's that since we can't look past the event horizon, we can't tell if there really exists a mathematical discontinuity in the universe or if something else is happening.
The problem I see with both special and general relativity is that it's an excellent mathematical method, but it's an ad hoc mathematical tool that cannot be extended beyond certain limits.
In relativity nothing can travel beyond light speed because that would imply an infinite energy, but that doesn't preclude some other mathematical solutions. However, if one assumes that space and time are quantized, then it seems like the existence of an absolute limit on the propagation speed of waves is necessary, from the Courant-Friedrichs-Lewy condition. This would be a limitation imposed by the structure of the universe itself, not from our calculations.
In Feynman's "Lectures on Physics" there's a chapter where he explains the concept of "curved" space with an analogy of ants living on a hot plate. Their measuring sticks expand and contract with temperature variations, so their measurements depend on the temperature gradient over the plate. Now suppose an ant engineer invented a new equipment, with a thermometer attached to the ruler which compensates for thermal expansion, they would discover they lived on a flat universe after all.
Starting with SR and its paradoxes, it seems pretty obvious that a theory that compensated for time and length variations would be welcome. Ten years after Einstein's death we discovered a universal velocity reference in the microwave background dipole, so one of the main tenets of special relativity is not true anymore. Perhaps this universal reference could be used to create a new theory separating the observer's perception of time and length from some absolute timespace which would be much simpler than our distorted measurements lead us to believe.
I believe the future lies in information theory. Assuming observable events happen in the universe, and assuming that causality exists, i.e. that if some event causes another that relation will exist under all circumstances, then we can think on how information about different events is transported through the universe. Again, this would be a truly absolute limit, not one imposed by our limitations in measuring and calculation.
There are about 10^500 possible string theories. We haven't yet found any that conform to all our observations. We don't know if it's even possible to search efficiently for that needle in the 10^500-big haystack, so string theory might be like the evil hall of mirrors in a bad B-movie: "yes, my childish nemesis, you falsified THIS one, but which one is the REAL string theory? HA HA HA!".
String theory may not be on a par with astrology, but IMHO it sullies the term theory. Anyone who has defended the theory of Evolution against fundies knows that's a bad move. It wouldn't be a bad idea to rename it string physics, even though arguably it's not physics yet either.
Expected time to finish is 1 hour and 60 minutes.
For instance, if we really did see a Crocaduck, that would pretty much be the end of the theory.
Yet, the theory persists despite the platypus.
"Dark matter" is not a theory. It is a label for a set of observed phenomena. Galaxies move as though they contained something that does not interact electromagnetically ("dark") but does interact gravitationally ("matter").
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
In relativity nothing can travel beyond light speed because that would imply an infinite energy,
Not exactly. In Relativity nothing with rest mass can travel at the speed of light because that would imply infinite energy.
Nothing at all, not even information, can travel faster than light because that implies that you could create scenarios where from certain reference frames, effects appear to happen before causes. As in time travel, or causality violation, and both Relativity theories (and the rest of physics) assumes causality to hold.
Ten years after Einstein's death we discovered a universal velocity reference in the microwave background dipole, so one of the main tenets of special relativity is not true anymore.
Not true. All Special Relativity says is that there is no preferred reference frame, as in the laws of physics must appear to hold true according to every observer. There is not one "special" reference frame where causality only needs to hold for it.
There was never anything in Relativity saying that there couldn't be some convenient reference against which to measure your velocity. Which is all the CMB dipole really is, and in the sense of what it implies for Relativity is no different than arbitrarily deciding the Andromeda Galaxy is our reference.
I believe the future lies in information theory.
The present and recent past lies is information theory. Information theory, which arose from QM, is fundamental to explaining many situations encountered today, like limits on the efficiency of irreversible calculations or the decay rate of black holes. However there is nothing in Information Theory that suggests information can travel faster than light. Indeed, quite the opposite, and this limit is key to understanding things like quantum entanglement and why it cannot be used for information transfer.
Assuming observable events happen in the universe, and assuming that causality exists, i.e. that if some event causes another that relation will exist under all circumstances, then we can think on how information about different events is transported through the universe. Again, this would be a truly absolute limit, not one imposed by our limitations in measuring and calculation.
That's pretty much how it's already done -- assume causality holds for all reference frames, and you can see that information cannot travel faster than light.
However at the end of the day no matter how elegant a mathematical model you have constructed, there are going to be variables whose values in our universe must be determined experimentally. Like c. You can get c via direct measurement, you can calculate it based on other constants which must themselves be measured. Either way.
Yet as our measurements get more precise, the values for these constants becomes more precise, and doesn't suddenly change values to something outside the error bars on previous less precise measurements. We're still depending on measurement, but we aren't going to up-end physical theories at some point when we hit the 32nd digit of c and suddenly nothing works.
This only seems like a problem if it bothers you for some reason that you can't derive all physical constants from a mathematical model, and instead the only way to know what values to place in that model of the universe is by actually looking at the universe.
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